1. Field of the Invention
The present invention is directed to a drive wheel for a frictionally driven belted track crawler, wherein the drive wheel is provided with a plurality of circumferentially spaced frictional engagement elements for engaging the flat surface of the belted track.
2. Description of the Prior Art
Conventional crawlers are well known and are typically provided with steel segmented track consisting of steel track shoes that are mounted to steel track chain. The track chain is positively driven by a drive sprocket which is coupled through a transmission to an internal combustion engine.
It has long been proposed to form endless belted tracks from elastomeric material. Such tracks have a number of advantages, one such advantage is that the belted tracks permit a crawler to drive over streets and curbs without ripping up the streets and curbs with the steel grousers of conventional tracks. A frictionally driven belted track system is currently marketed by Caterpillar Tractor Co. of Peoria, Ill. on an agricultural tractor, see PCT Application W085/02824. With this track system, the belted track engages a rubber coated main drive wheel located at the rear of the crawler and a pneumatic tire idler wheel located at the front of the tractor. The track is provided with a centering guide lug and flat surfaces to engage the rubber coated portions of the main drive wheel.
Frictionally driven belted track system are subject to slippage between the main drive wheel and the track. As such, the belted track is put under great tension to increase the normal force between the main drive wheel and the track to reduce slippage. Slippage still may occur under increased tension force, as the track and drive wheel become covered with mud, slime, water and other slippery materials. Scrapers for scraping mud from the track and main drive wheel may be used to reduce this problem. In addition main drive wheels having drain openings have also been proposed to further alleviate at least some of this problem. Another proposal for reducing slippage is to drive the idler wheel, as disclosed in U.S. Pat. No. 4,986,377.